Colloidal Magnetic Heterostructured Nanocrystals with Asymmetric Topologies: Seeded-Growth Synthetic Routes and Formation Mechanisms

Abstract

Colloidal inorganic nanocrystals (NCs), free-standing crystalline nanostructures generated and processed in solution phase, represent an important class of advanced nanoscale materials owing to the flexibility with which their physical-chemical properties can be controlled through synthetic tailoring of their compositional, structural, and geometric features and the versatility with which they can be integrated in technological fields as diverse as optoelectronics, energy storage/conversion/production, catalysis, and biomedicine. In recent years, building upon mechanistic knowledge acquired on the thermodynamic and kinetic processes that underlie NC evolution in liquid media, synthetic nanochemistry research has made impressive advances, opening new possibilities for the design, creation, and mastering of increasingly complex "colloidal molecules," in which NC modules of different materials are clustered together via solid-state bonding interfaces into free-standing, easily processable multifunctional nanocomposite systems. This review will provide a glimpse into this fast-growing research field by illustrating progress achieved in the wet-chemical development of last-generation breeds of allinorganic heterostructured nanocrystals (HNCs) in asymmetric non-onionlike geometries, inorganic analogues of polyfunctional organic molecules, in which distinct nanoscale crystalline modules are interconnected in heterodimer, hetero-oligomer, and anisotropic multidomain architectures via epitaxial heterointerfaces of limited extension. The focus will be on modular HNCs entailing at least one magnetic material component combined with semiconductors and/or metals, which hold potential for generating enhanced or unconventional magnetic behavior, while offering diversified or even new chemical-physical properties and functional capabilities. The available toolkit of synthetic strategies, all based on the manipulation of seeded-growth techniques, will be described, revisited, and critically interpreted within the framework of the currently understood mechanisms of colloidal heteroepitaxy.

Synthesis of Colloidal Molecules: Recent Advances and Perspectives

“…Biphasic crystals (AX‐type CMs) are predominantly obtained, but the number of satellites can reach the value of 4 even 6. Generally, the larger the seed and/or the lower the solvent polarity, the higher the satellite number . But in other systems, the control parameters are the temperature and/or relative precursor to seed proportions.…”

“…seed and/ort he lower the solvent polarity,t he higher the satellite number. [6] But in other systems, the control parameters are the temperature and/orr elative precursor to seed proportions. Nevertheless, the satellite crystals are generally regular nor in size and shape, neither in their positions on the seed surface.…”

“…We propose here an update by reviewing the most significant works published these last eight years. The reader has to refer to our previous review to embrace the full story and/or to read other excellent recent reviews written by others and addressing the field from other angles …”

“…The readerh as to refer to our previousr eview [4] to embrace the full story and/or to read other excellent recentr eviews written by others and addressing the field from other angles. [5][6][7][8][9][10][11][12][13]…”

Metal/semiconductor interfaces in nanoscale objects: synthesis, emerging properties and applications of hybrid nanostructures

“…Since the chemical principles of nanoscale synthesis have been reviewed, 44 we will emphasize the mechanisms of growth and precise control over the formed interfaces between metals and semiconductors (with a special focus on the II-VI family-the metal-chalcogenide (O, S, Se, Te) materials and formation of anisotropy or asymmetry). We refer the reader to excellent reviews by Cozzoli and co-workers, 45,46 Manna and co-workers, 47 and Banin and co-workers, 48 who set the groundwork for the description of hybrid nanostructures, and a recent review from Zhang and co-workers on epitaxial multicomponent HNSs. 49 These studies give a broad overview of the development of the eld and various possible interfaces that can form alongside thermodynamic requirements for the growth of HNSs.…”